1. Field of the Invention
The present invention relates to a steering device for vehicles. More particularly, it relates to a steering device including a cam member for cancelling or disabling the operation of automotive turn signal switches, for improving an assembling or mounting work when the steering device is mounted on a motor vehicle.
2. Description of the Prior Art
Recently, a steering device for vehicles is provided on a steering wheel with various electric elements such as switches or electric instruments such as an air bag means. In such a steering device, an electric connecting means for maintaining an electric connection between the rotating steering wheel and a fixed member such as a steering column fixed to a vehicle body is inevitable.
For instance, Japanese Utility Model Laid-Open No. 60-114048 and U.S. Pat. No. 4,422,699 show automotive steering devices provided with such a connecting means.
This known steering device has a steering rotative unit that is rotatable together with a steering wheel and is disposed coaxially with a steering shaft, a steering non-rotative unit that is disposed coaxially with a steering shaft and is fixed to a vehicle body member such as a steering column, a combination switch means that is disposed coaxially with the steering shaft, is fixed to a vehicle body member and includes in combination turn signal switches and other switches, and a turn signal switch cancelling mechanism having an operating section provided on an inner wall of the combination switch means.
The steering rotative unit is provided with a rotative case that is rotatable together with the steering shaft. The non-rotative unit is provided with a stationary case. Both the cases are assembled slidably relative to each other and are adapted to define an annular receiving compartment that is coaxial with the steering shaft. Connectors are provided on the rotatable case and the fixed case, respectively. A flexible electric path in a spiral form is arranged coaxially with the steering shaft within the annular receiving compartment. Opposite ends of the flexible electric path are connected to the connectors.
In such a known steering device, a brushless electric signal transmission means is composed of the rotatable case, the fixed case, the flexible electric path and the connectors. The steering device is characterized in that the operating section of the turn signal switch cancelling mechanism is connected to or engaged with the rotatable case of the brushless electric signal transmission means so as to rotate together with the rotatable case.
However, in the steering device, since the rotatable member such as the rotatable case is interposed between the steering wheel and the operating section of the turn signal cancelling mechanism and serves as a rotational torque transmission means for driving the operating section, the turn signal switch cancelling mechanism is liable to be subjected to an excessive vibration from the movable member. Thus, if such a steering device is used for connecting means for keeping the electric connection operative in the vehicle, then the reliability and the durability will deteriorate. In order to solve this problem, the mechanical strength must be increased, resulting in an increase of the weight and the manufacture cost of the device.
Also, in assembling the known steering device, it is necessary to carry out an adjustment of the relative angular position between the cam member connected to the operating section of the turn signal switch cancelling mechanism and the steering wheel in the rotational directions of the steering shaft.
For example, FIG. 6 schematically shows a known steering device similar to the above-described steering device.
The steering device shown in FIG. 6 is composed of a steering shaft 12 rotatably inserted into a fixed member of a vehicle body such as a steering column 10, a steering wheel 11 coupled to an upper end of the steering shaft 12, a receiving case 14 that constitutes a brushless electric signal transmission means and is rotatable together with the steering wheel 11, a combination switch 13 and a cam member 15 serving as a turn signal switch cancelling mechanism.
In such a steering device, it is necessary to increase the signal transmission capacity corresponding to the increase in numbers of the electric elements and electric instruments on the steering wheel 11 as described before. Also, the receiving case 14 serving as the brushless electric signal transmission means is large in size and its dimension t axially of the steering shaft 12 is increased. For this reason, the cam member 15 for the turn signal switch cancellation is located at a deep position within a central hole of the receiving case 14. It would, therefore, be difficult to angularly position the cam member 15 relative to the steering wheel 11 in the rotational direction of the steering shaft 12. As a result, it would be necessary to position the cam member 15 in place relative to the steering wheel 11 using a special jig or tool.
As described above, the known devices suffer from a problem in assembling work.